1. Field of the Invention
This invention relates to a protective bellows with reduced volume for hinged joints, particularly for the front wheel drive of a motor vehicle. More particularly, it relates to a rubber protective element for tripod or ball universal joints, the volume of the bellows being as small as possible while permitting large clearances with a minimum of wear of the protective element.
2. Description of the Prior Art
To avoid this difficulty, bulky universal joint covers are generally used on the side of the wheel, which requires the use of a large amounts of grease inside this type of bellows.
Another current practice resides in the use of bellows of smaller volume having folds whose walls form acute angles at rest. The drawback of this arrangement resides in the fact that the outer ends or tops of the folds come into contact when turning the wheels. Since these areas are in rotation in relation to one another, wear of the outer walls of the cover, as well as an embrittlement and possibly premature failure, result, with a consequential loss of the grease contents, and the risk of foreign bodies being admitted into the universal joints.
There can also occur an inner abrasion due to a contact of the inner ends or hollows of the folds on the sharp edges of the tripod, particularly in sharp turns. Thus, it appears that for each turn of the bellows, the folds are subjected to both a very closed angle of compression and a very open angle of expansion in the stretched part.
This contributes to imposing on the folds at each turn, a wide range of folding angles which goes from a completely closed angle in the compression zone to an almost flat angle in the spread zone.
It is therefore desirable, for increasing the life of the bellows, to reduce these large clearances and thereby limit the stresses at the tops and hollows of the folds.